Composition for deinking waste paper

ABSTRACT

Waste paper is effectively deinked by contact with an aqueous treating composition containing an N-alkyllactam solvent at a temperature of from about 110°F to about 210°F. The N-alkyllactam solvent is not consumed in the treating process and can be effectively separated from the waste material removed from the paper being treated for reuse in the contacting of additional quantities of waste paper. The use of N-cyclohexyl pyrrolidone, N-t-butyl pyrrolidone and N-t-octyl pyrrolidone is particularly advantageous in that simplified regeneration techniques of appreciable technical and economic significance can be employed therewith. The aqueous treating composition will generally contain from about 0.5 to about 200 parts by weight of water, from about 0.05 to about 1 part by weight of a water-soluble, non-volatile, inorganic ionic compound, e.g., NaOH, and from about 1 to about 99 parts by weight of the N-alkyllactam solvent. The deinking is carried out at a temperature of from about 110°F to about 210°F. Difficult-to-deink grade material, such as waste paper containing thermoplastic and elastomeric coatings, laminates and adhesives, can be effectively and conveniently deinked by the N-alkyllactam solvent composition.This is a division of application Ser. No. 502,657, filed November 1, 1972 now U.S. Pat. No. 3,846,227.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the deinking of waste paper. Moreparticularly, it relates to a novel composition and process for thedeinking of waste paper, including difficult-to-deink paper.

2. Description of the Prior Art

The recycling and reuse of waste paper is an important environmentalaspect of the enormous and continually growing use of paper in nearlyall aspects of modern business and social activities. This conversion ofwaste paper to fibrous material, advantageously of a quality essentiallyequivalent to virgin pulp, involves what is generally known in the artas "deinking". In conventional deinking operations, printed, colored andcoated paper is generally treated with hot, alkaline, aqueous solutionsgenerally containing a variety of additives, such as detergents,emulsifiers, dispersants and the like. Such operations are reasonablysatisfactory in the deinking of paper that is practically free of thevariety of synthetic thermoplastic and elastomeric substances nowincreasingly used in printing inks, functional coatings, laminates,adhesives, etc. The conventional deinking compositions are not suitable,however, for the acceptable deinking of so-called difficult-to-deinkgrade materials, namely those waste paper materials having suchsynthetic thermoplastic and elastomeric substances associated therewithas is increasingly the case with respect to the inks, coatings,laminates, adhesives and the like increasingly used in wide varieties ofmodern paper applications.

The failure to adequately remove the various contaminating substancesassociated with difficult-to-deink grade waste paper results in theirbuild-up in the paper making system in which the recycled material isbeing incorporated, thereby causing costly and time-consuming breaks onthe paper-making machine and the production of non-saleable paper ofsubstandard quality, i.e., so-called "broke". As a result, the deinkingof waste paper by conventional techniques is frequently confined towaste paper not having such synthetic, thermoplastic and elastomericsubstances thereon that can not be effectively removed by conventionaldeinking compositions and techniques. As a result, the lower quality,more difficult-to-deink grade waste papers are not generallyreprocessed, despite their generally less expensive nature and the evergrowing need for the processing of such waste on the basis of bothcommercial and environmental consideration.

It is an object of the present invention, therefore, to provide animproved process and composition for the deinking of waste paper.

It is another object of the invention to provide an improved process andcomposition of particular utility with respect to the deinking ofdifficult-to-deink grade material.

It is another object of the invention to provide a process andcomposition for the effective removal of synthetic thermoplastic andelastomeric substances from the waste paper being treated.

With these and other objects in mind, the invention is hereinafter setforth in detail, the novel features thereof being particularly pointedout in the appended claims.

SUMMARY OF THE INVENTION

N-alkyllactams have been found highly effective in the deinking of wastepaper, particularly in the treatment of difficult-to-deink gradematerials. The N-alkyllactams may be employed in amounts of generallyfrom about 0.5% to about 99.5% by weight, based on the total weight ofthe aqueous treating composition in which they are employed, withamounts of from about 3/4% to about 25% by weight being particularlyadvantageous in many deinking applications. The effectiveness of theN-alkyllactam solvent is enhanced by the incorporation in the aqueoustreating composition of a small amount of sodium hydroxide or othersuitable water-soluble, non-volatile, inorganic ionic compound. Theaqueous treating composition and the waste paper being treated arecontacted at a temperature within the range of from about 110°F to about210°F. The N-allkyllactam solvent employed in the practice of theinvention is not consumed and can be recovered for reuse in thecontacting of additional quantities of the waste paper being deinked,Particularly advantageous overall operations are achieved by the use ofN-cyclohexyl pyrrolidone, N-t-butyl pyrrolidone or N-t-octyl pyrrolidonein that the particular lactam solvents have an additional advantage inthe convenient and economically significant manner in which they can berecovered for continuous recycle and reuse.

DETAILED DESCRIPTION OF THE INVENTION

The deinking of waste paper, particularly the deinking ofdifficult-to-deink grade waste paper, is significantly improved andenhanced, in the practice of the present invention, by the use ofN-alkyllactam solvents in the aqueous treating composition employed. Theexceptional solventing action of the N-alkyllactam solvents causes thewaste paper being treated to become readily deinked so that anacceptable pulp product can be withdrawn from the subsequent washingstages, leaving a used N-alkyllactam solvent composition that can beeffectively regenerated and reused in the treatment of additionalquantities of the paper being deinked. In particular embodiments of thepresent invention, as herein discussed, particularly economical recoveryof the lactam solvent can be achieved, enhancing the overall operationfor the continuous deinking of waste paper.

In the practice of the present invention, the N-alkyllactam solventemployed in the aqueous treating composition is preferably an N-alkylpyrrolidone or N-alkyl piperidone, having generally from about 1 toabout 16 carbon atoms in the alkyl group, said alkyl group includingN-cycloalkyl groups. Most generally preferred are the N-lower alkylgroups of 1 to 6 carbon atoms, including N-lower cycloalkyl groups, suchas the N-cyclohexyl group. Illustrative of the various N-lower alkyllactams thus suitable for use in the practice of the present inventioninclude, but are not limited to, the following illustrative examples:N-cyclohexyl pyrrolidone, N-t-butyl pyrrolidone, N-t-octyl pyrrolidone,N-methyl pyrrolidone, N-ethyl pyrrolidone, N-propyl pyrrolidone,N-isopropyl pyrrolidone, N-n-butyl pyrrolidone, N-n-hexyl pyrrolidone,N-n-octyl pyrrolidone, N-n-isooctyl pyrrolidone, N-n-decyl pyrrolidone,N-undecyl pyrrolidone, N-dodecyl pyrrolidone, N-tetradecyl pyrrolidone,N-hexadecyl pyrrolidone, N-methyl piperidone, N-ethyl piperidone,N-propyl piperidone, N-isopropyl piperidone, N-t-butyl piperidone,N-n-butyl piperidone, N-n-hexyl piperidone, N-n-octyl piperidone,N-isooctyl piperidone, N-n-decyl piperidone, N-undecyl piperidone,N-dodecyl piperidone, N-tetradecyl piperidone, N-hexadecyl piperidone,and the like.

The N-alkyllactam solvents employed, i.e., the N-alkyl pyrrolidones andN-alkyl piperidones, are lactams of the gamma- and delta- amino acidderived from butyric acid, valeric acid and caprylic acid. Since suchsubstances are cyclic acid amides, they are neutral and, therefore,serve in the practice of the present invention as physically dissolvingabsorbents, such substances having a particular affinity for thedissolving of printing inks and the various synthetic, thermoplastic andelastomeric substances frequently employed with printing inks,laminates, adhesives, and the like frequently encountered indifficult-to-deink grade, lower quality paper waste material, in theprocessing of which the present invention represents a highlyadvantageous and commercially significant advance in the art.

In carrying out the waste paper deinking of the present invention, theamount of pulp being treated will generally range from about 1% to about20% by weight or more based on the weight of the aqueous treatingcomposition employed. Higher pulp contents are generally not feasibledue to the mechanical limitations of the pulping equipment. Thepulp/treating composition ratio employed in any given application willvary depending upon a number of factors, such as the quality of thepaper to be deinked, the particular lactam solvent employed, the amountof lactam solvent employed, the contacting temperature, the nature andquantity of other ingredients, such as known conventional pulping liquoringredients, employed and the like. In this regard, it should be notedthat the N-alkyllactam solvent can be employed in widely varyingproportions, generally ranging from about 0.5% to about 99.5% by weightbased on the total weight of the aqueous treating composition.N-alkyllactam solvent contents of from about 0.5% to about 50%,frequently from about 3/4% to about 25% by weight based on the totalweight of the aqueous treating composition are suitable and advantageousin many applications.

In conventional deinking compositions, caustic soda is ordinarilyemployed together with conventional additives such as detergents oremulsifiers to supplement the action of the caustic soda. In thedeinking of waste paper through the use of N-alkyllactam solvents asherein provided, the solvent action of the N-alkyllactam solvents isenhanced by likewise employing the caustic soda of the conventionaldeinking composition in the aqueous treating composition of the presentinvention. The enhanced deinking action of the N-alkyllactam solventscan be achieved, however, not only with said caustic soda, or in analkaline solution in general, but in aqueous treating compositionscontaining a wide variety of inorganic, non-volatile, water-solubleionic compounds. Such compounds are, in general, those containing acation taken from Groups I, II and III of the Periodic Table. Suitablecompounds for use in the aqueous treating compositions of the presentinvention include, but are not necessarily limited to such compoundscontaining a cation taken from the group consisting of sodium,potassium, calcium, iron, aluminum and magnesium. Representativecompounds illustrating the compounds thus suitable for use in enhancingthe deinking effectiveness of N-alkyllactam solvents in particularembodiments of the invention include the generally preferred NaOH, KOH,Ca(OH)₂, FeCl₃, Al₂ (SO₄)₃, Na₃ PO₄, Na₂ CO₃, Mg(OH)₂, K₂ CO₃ and thelike. It is believed that the incorporation of ionic compounds of thisgeneral character serves to reduce the water solubility of theN-alkyllactam solvent in the aqueous treating composition at theoperating conditions employed in the practice of the invention. Thesolvent is thereby rendered available in undissolved form for highlyeffective paper deinking and pulping action, it being understood thatthe water serves as a carrier to facilitate the desired contacting ofthe N-alkyllactam solvent with the waste paper being treated.

In such generally preferable embodiments, the subject aqueous treatingcompositions will generally contain from about 0.5 to about 200 parts byweight of water, from about 0.05 to about 1 part by weight of saidinorganic compound as indicated above, and from about 1 to about 99parts by weight of the N-alkyllactam solvent. In many applications, thelactam solvent content will range from about 1 to about 200 parts byweight, with a lactam solvent content of from about 3/4% to about 25% byweight based on the total weight of said aqueous treating compositionfrequently being sufficient as noted above. It should also bespecifically noted that it is within the scope of the present inventionto incorporate conventional deinking composition additives in thecompositions of the present invention for their intended purpose. Thus,conventionally employed detergents, surfactants, emulsifiers and thelike can also be employed in conventional amounts for their usualpurpose in the deinking compositions of the present invention. Forexample, it has been found generally advantageous to employ up to about0.2 parts by weight surfactant in the generally preferred aqueoustreating composition indicated hereinabove.

In the deinking process herein disclosed and claimed, the waste paperbeing treated and the aqueous treating composition are contacted at anelevated treating composition temperature generally within the range offrom about 110°F to about 210°F, advantageously from about 120°F toabout 200°F. While the operating temperature can thus vary ratherwidely, it has been found that the heating of the aqueous treatingcomposition to from about 150°F to about 170°F is generally convenientin many practical applications of the invention. It should also be notedthat it is within the scope of the present invention to treat the paperto be deinked with, for example, an aqueous caustic treating solution ina preliminary treating operation to at least partially pulp the wastepaper being treated prior to addition of the N-alkyllactam thereto toform the aqueous treating composition of the present invention. In suchan embodiment, for example, the waste paper to be treated can bepre-treated with a caustic solution at room temperature and pressed toremove a portion of the treating liquor therefrom prior to addition ofthe N-alkyllactam solvent thereto and heating to the indicatedtemperature. In such instances, the lactam solvent can be sprayed orotherwise added to the moist pulp, the preliminary pressing serving toreduce the amount of liquid to be heated in providing for the desiredcontacting of the aqueous treating composition with the paper beingtreated at the indicated conditions, effecting a further economy in thepractice of the invention.

The deinking process of the present invention employing the aqueoustreating composition of the invention comprises generally the contactingof the waste paper being treated with the aqueous treating compositionin a pulping zone, the separation of a major portion of the aqueoustreating composition from the resulting pulp, the subsequent washing ofthe pulp, and the recovery, regeneration and recycle of N-alkyllactamsolvent for the continuous treatment of additional quantities of wastepaper to be deinked. In general, the portion of the aqueous treatingcomposition initially separated from the treated pulp, as in aconventional press, can be recycled directly back to the pulping zone.The wash water subsequently removed from the washing zone in which thetreated pulp is washed will contain additional quantities of theN-alkyllactam solvent that should be recovered in highly desirable,economically advantageous commercial embodiments of the invention. Thesolvent thus present in the wash water will, it should be noted, containthe various contaminants and other waste materials removed from thepaper being treated for ultimate passage from the treating system anddisposal as waste material. In the separation of the N-alkyllactamsolvent from the wash water and from said waste material, the wash waterremoved from the washing zone is conveniently passed to an evaporatorzone in which the wash water solution may be concentrated as by vacuumevaporation of a portion of the water content thereof. The concentratedaqueous solution of N-alkyllactam solvent with dissolved waste materialcan thereupon be processed, as by a conventional distillation, torecover a purified N-alkyllactam solvent-water stream separated from thewaste material removed from the treated pulp. When employingN-cyclohexyl pyrrolidone, N-t-butyl pyrrolidone and N-t-octylpyrrolidone as the N-alkyllactam solvent of the invention, theproperties of these particular lactam solvents enable the hotconcentrated wash solution obtained upon preliminary evaporation to beseparated into two separate and distinct liquid layers or phases uponheating to the so-called cloud point temperature associated with each ofthese particular lactam solvents. The cloud point represents thetemperature at which the concentrated aqueous solution of the indicatedlactams separates into a first, water-rich layer and a second,solvent-rich layer that can readily be separated from each other. Thesolvent-rich layer containing, therefore, a substantial proportion ofthe waste material present in the wash water solution can thereafter bepurified by economically advantageous methods, such as by filtration,carbon adsorption, evaporation and the like, to obtain a purified orregenerated lactam solvent-water stream that can readily be recycledback to the pulping zone for contact with additional quantities of thepaper being deinked. Such more economical recovery and regeneration,permissible because of the indicated phase separation resulting from thecharacteristics of said N-cyclohexyl pyrrolidone, N-t-butyl pyrrolidoneand N-t-octyl pyrrolidone, represent a further highly significantadvantage obtained in the practice of the present invention foreffectively deinking waste paper, particularly the lower quality, moredifficult-to-deink grade, less expensive paper materials with respect towhich the present invention is of particular significance.

For purposes of the desired phase separation of the wash solution inparticular embodiments of the invention, the aqueous wash solution isconveniently passed into a quiescent zone in which the indicatedseparation into distinct water-rich and solvent-rich layers occurs. Aspreviously indicated, the aqueous wash solution from the washing zonewill generally be initially concentrated by evaporation of a portion ofits water content and thereafter heated to its cloud point temperature.It will be understood, however, that in some instances it might not benecessary or desirable to initially concentrate the aqueous washsolution, particularly when a relatively small amount of wash water isemployed. Similarly, it might be advantageous and sufficient toconcentrate the wash solution to a specified degree, but not necessaryto further heat the hot concentrated solution in that the temperaturethereof is at or in excess of the cloud point temperature of theparticular solution. The cloud point temperature of aqueous solutions ofthe specified lactam solvents thus represents not a fixed and inflexibletemperature point, but a temperature dependent upon a number ofoperating factors such as the particular lactam solvent employed, theproportion of said solvent and of water in the aqueous wash solution,the nature and amount of waste materials removed from the paper beingtreated that are present in the wash solution, and the like. In thepractice of the present invention, the cloud point temperature of agiven aqueous wash solution will be readily apparent to those skilled inthe art employing a particular lactam solvent in a given deinkingapplication employing specific conditions for the washing of the treatedpulp.

The invention is hereinafter described with respect to the use ofpreferred N-alkyllactam solvent and with reference to the accompanyingdrawing, it being understood that the paper being deinked may beprinted, colored and coated paper such as is treated in conventionaldeinking operations, but advantageously is such paper containingsynthetic, thermoplastic and elastomeric substances not successfullyaccommodated in conventional operations. The contaminants resulting fromthe increasing use of a variety of said synthetic, thermoplastic andelastomeric substances in inks, functional coatings, laminates,adhesives and the like render such paper to be treateddifficult-to-deink grade material. Such material is generally notprocessed in conventional deinking operations, but may be treated toadvantage in the practice of the present invention. The invention hasparticular significance, therefore, in the deinking of suchdifficult-to-deink grade material. In the drawing, waste paper to bedeinked is passed to conventional pulper 10 through line 12 for contacttherein with an aqueous treating composition containing an N-alkyllactamsolvent at a composition cooking temperature of from about 110°F toabout 210°F. Treated pulp and cooking liquor are passed from pulper 10through line 14 to press 16 wherein a major portion of the aqueoustreating composition is squeezed from the pulp for recycle through line18 to pulper 10 for contact with additional quantities of waste paper tobe treated. The pressed pulp leaving press 16 through line 20 passes towashing zone 22 for counter-current contact therein with wash water toremove N-alkyllactam solvent, together with waste material removed fromthe paper being treated, from the treated pulp, which is withdrawn fromwashing zone 22 through line 24.

The wash water solution removed from washing zone 22 through line 26thus contains lactam solvent advantageously to be recovered and reusedin the economical operation of the deinking process of the presentinvention. The wash water can be concentrated, as in vacuum evaporator28, to produce a hot, concentrated wash solution that is passed throughline 30 to quiescent zone 32 in which the highly advantageous phaseseparation, achievable when employing the preferred solvents specified,is accomplished. If necessary or desired, the hot wash water concentratefrom evaporator 28 can be further heated to reach the cloud pointtemperature under the particular circumstances pertaining to a givenconcentration of the particular preferred N-alkyllactam solvent employedand a given amount of particular waste materials associated therewith.Water vapor removed from evaporator 28 in the concentration of the washsolution can be condensed and recycled through line 34 to washing zone22 for use in the washing of additional quantities of pulp.

The upper, water-rich layer in zone 32, having a small amount of solventand some accompanying waste material present therein, can be withdrawnthrough line 36 for recycle to pulper 10. The bottom, solvent-rich layerin zone 32 is withdrawn through line 38 for solvent purificationtreatment by the removal of waste materials therefrom in solventpurification zone 40. Separated waste materials are withdrawn from saidzone 40 through line 42 for discharge. Such wastes constitute theaccumulation of inks, coatings and the like removal from the treatedpaper, including the synthetic, thermoplastic and elastomeric substancesused in the inks, coatings, laminates and adhesives associated withdifficult-to-deink grade material treated in accordance with theinvention. A purified solvent/water stream is withdrawn from said zone40 through line 44 for recycle to pulper 10. As shown in the drawings,therefore, the purified solvent stream in line 44, the water-rich streamin line 36, and makeup caustic or other inorganic admixture agent inline 46 can all be fed, at appropriate rates, to pulper 10, togetherwith recycle cooking liquor in line 18, as is illustrateddiagrammatically in the drawing by common recycle line 48 to pulper 10.

As is shown also in the drawings, the waste paper to be deinked can alsobe passed through line 12a to pulping zone 10a for pulping with anaqueous alkaline solution, e.g., a caustic solution, generally at roomtemperature, prior to deinking with the aqueous treating composition ofthe invention at the more elevated temperatures herein generallydisclosed and claimed. The thus pre-treated pulp, in this embodiment, isadvantageously passed through line 14a to press 16a for removal of aportion of the aqueous pre-treatment solution prior to passage, asthrough line 14b to contacting zone 10 for cooking with the aqueoustreating composition containing N-alkyllactam solvent in accordance withthe teachings of the present invention. The alkaline pre-treatmentsolution removed from the pulp in said press 16a can be recycled topulping zone 10a for contact with additional quantities of waste paper.

It is within the scope of the invention to employ any one of severalconvenient techniques for the removal of waste materials from thesolvent-rich stream passed to solvent purification zone 40. For example,it is found that filtration of said solvent-rich stream results in theremoval of sufficient waste material to provide a purified solvent-waterrecycle stream suitable for recycle and reuse in the treatment ofadditional quantities of waste paper. The provision of a carbonadsorption bed in said zone 40 can likewise be employed in thepurification of the solvent-rich stream withdrawn from quiescent zone32. Solvent purification zone 40 can also comprise an evaporation zonefrom which a purified solvent-water stream can be withdrawn andcondensed for said recycle and reuse. Said zone 40 may also, if desired,comprise a distillation zone although the simpler, less expensivemethods of purification hereinabove indicated are generally preferredfrom an economic viewpoint. When less preferred lactam solvents, i.e.,those not having the cloud point characteristics of phase separationmentioned above, are employed in the process of the invention, theconcentrated wash water solution will generally be distilled to producea purified solvent stream for recycle to pulper 10.

The invention is hereinafter described with reference to examplesillustrating particular embodiments thereof, it being understood thatthe examples should not be construed as limiting the scope of theinvention as hereinafter set forth in the appended claims. Unlessotherwise indicated, the proportions of materials employed are inpercent by weight. In addition to visual examinations of treatedmaterial, brightness measurements have also been taken in accordancewith TAPPI suggested methods on a Hunter D-40 Reflectometer using bothblue and green filters. Brightness/color was also measured in accordancewith TAPPI suggested procedures on a Hunter D-25 Color Difference Meterfor L = brightness, a = red/green, and b = blue/yellow.

EXAMPLE 1

A specially prepared testing grade of waste paper, obtained from FortHoward Paper Company consisting of color printed, over varnish labelstock repulped to give uniform sheets having a profusely color-speckedappearance was employed, said paper being deemed by those in the art asvery difficult to reclaim, i.e., difficult-to-deink, grade material. Thedeinking method employed was similar to that given in TAPPI Monograph 31"Introduction to Deinking", page 151, Example 1, which correlates withdeinking in a 16 ft. Hydrapulper at 190°F using 4% caustic soda owf (onweight of fiber) on waste paper at 8% consistency, i.e., paper solids inthe cooking liquor. Three grams (dry) of said deinking stock, 30 ml. of3% caustic soda solution, specified amounts of water and of theN-alkyllactam pyrrolidone were cooked for 1 hour at 170°F withadditional water added to compensate for evaporation loss. The blend wasrun for 2 minutes at "Blend" speed in an Osterizer Classic VIII ModelBlender. 600 ml. of water was added and a sheet of the treated materialwas formed on 60 mesh, vacuum sheet mold. The newly formed sheet waswashed twice using 1 liter of water for each wash, reforming the sheetbetween washes. The reformed sheet was pressed and dried in a paperdrier. The resultant paper from the sheet mold, called scan sheets, weretested for deinking efficiency by measuring brightness as indicatedabove. The sheets were also individually rated for colored speckremoval, which is not readily apparent from the above instrumentalmeasuring techniques. In one series of runs, the results of which areset forth in Table I, varying amounts of cyclohexyl pyrrolidone (CHP)were employed, the results indicating the effectiveness of said CHP forthe desired deinking of difficult-to-deink grade material.

                                      Table I                                     __________________________________________________________________________    Variation in CHP Content                                                      Vol. %                                                                             Hunter D-40                                                              CHP in       Hunter D-25                                                      Cooking                                                                            Blue                                                                              Green             Visual Rating                                      Liquor                                                                             Filter                                                                            Filter                                                                            L   a    b    for Specks                                         __________________________________________________________________________    0    62.4                                                                              69.6                                                                              84.8                                                                              -2.96                                                                              +5.47                                                                              heavy color specks                                 2.5  69.7                                                                              77.1                                                                              89.6                                                                              -3.11                                                                              +5.66                                                                              no color specks                                    10   68.7                                                                              77.5                                                                              89.7                                                                              -3.26                                                                              +7.12                                                                                "                                                25   71.8                                                                              79.8                                                                              90.7                                                                              -1.47                                                                              +6.09                                                                                "                                                __________________________________________________________________________

The effectiveness of CHP in the deinking of difficult-to-deink gradematerial, as shown in Table I, was further indicated in another seriesof runs in which the cooking time and temperature were varied. Each setof time/temperature condition runs was performed with control samplescontaining no CHP and samples containing 10% CHP by volume in thealkaline cooking liquor. The results are as shown in Table II below.

                                      Table II                                    __________________________________________________________________________    Variation in Cooking Time and Temperature                                     % CHP    Cooking Evaluation of Paper Following Treatment                      in               Hunter D-40                                                                           Hunter D-25                                          Test                                                                              Cook Temp.                                                                             Time                    Visual Rating for Specks                 No. Liquor                                                                             (°F.)                                                                      (min.)                                                                            Blue                                                                              Green                                                                             L   (-)a                                                                              (+)b                                                                              and Base Sheet Color                     __________________________________________________________________________    1.   0   170 60  61.5                                                                              68.2                                                                              84.1                                                                              3.49                                                                              5.02                                                                              very many color specks                   2.  10   170 60  70.3                                                                              78.1                                                                              90.2                                                                              3.64                                                                              6.15                                                                              no color specks - pract. white           3.  10   170 30  68.7                                                                              77.2                                                                              90.2                                                                              4.61                                                                              6.61                                                                              no color specks - green tint             4.  10   170 15  69.5                                                                              78.4                                                                              90.6                                                                              3.70                                                                              6.94                                                                                   "                                   5.  10   170 10  68.3                                                                              77.4                                                                              90.0                                                                              4.12                                                                              7.25                                                                                   "                                   6.  10   170  5  65.4                                                                              72.4                                                                              87.2                                                                              4.42                                                                              5.64                                                                              many tiny specks - green tint            7.   0   150 60  58.9                                                                              64.5                                                                              81.8                                                                              3.35                                                                              3.75                                                                              very many color specks                   8.  10   150 60  70.3                                                                              78.7                                                                              90.7                                                                              3.65                                                                              7.09                                                                              no color specks - pract. white           9.  10   150 30  68.1                                                                              77.3                                                                              89.9                                                                              5.32                                                                              6.04                                                                              some green specks - green tint           10. 10   150 15  63.0                                                                              71.0                                                                              85.8                                                                              6.54                                                                              4.78                                                                              some green flakes - moderately                                                green                                    11.  0   125 120 61.2                                                                              64.9                                                                              82.4                                                                              2.71                                                                              4.06                                                                              very many color specks                   12. 10   125 120 66.7                                                                              72.3                                                                              86.9                                                                              6.95                                                                              4.78                                                                              apprec. green flakes - slightly                                               green                                    13. 10   125 60  63.9                                                                              68.8                                                                              85.1                                                                              7.31                                                                              4.51                                                                              many green flakes - slightly             __________________________________________________________________________                                         green                                

The results shown in Table II show that the presence of N-cyclohexylpyrrolidone in the cooking liquor is essential to the effective deinkingand removal of color specks even under the maximum cooking conditionsemployed, namely 170°F for 60 minutes. As shown by the results of TestNo. 5, the cooking time at 170°F can be reduced to 10 minutes with allcolor specks removed and very good results in the brightnessmeasurements. Alternatively, Test No. 8 indicates that the temperaturecan be reduced to 150°F with very good deinking effectiveness at acooking time of 60 minutes under the test conditions employed. As shownby the results of from 11-13, the effectiveness of the deinkingoperation is reduced at a cooking temperature of 125°F, even whenemploying a longer cooking cycle. The cooking liquor composition of thepresent invention was, nevertheless, more effective than theconventional cooking liquor composition at such lower temperatureconditions, at equal cooking cycles of 120 minutes and when employing acooking cycle of 60 minutes for the composition of the present inventionas compared with the 120 minute cycle for the control cookingcomposition.

In another set of similar runs under the indicated conditions, thedeinking composition of the present invention was used in the deinkingof other substrate materials in place of the color printed, overvarnished label stock referred to above and used in the test runs setforth in Tables I and II. In these runs, the waste stock treated wasmixed colored paper, photomount and phenolic waste stock. The mixedcolored paper comprised light orange, deep orange, deep red, deep blueand light green, and 10 pt. board sized, 0.5 grams each color mixed foreach test. The Photomount comprised 20 pt. white board coated on oneside with a dark green heat shield adhesive. The Phenolic waste stockcomprised phenol formaldehyde kraft board, 50% saturated, not cured. Redtray stock 20 pts., tan body separator 25 pts., 1.5 grams each typemixed with 3.0 grams total for each test. The brightness change is shownby the Hunter D-40 Blue filter reading and the Hunter D-25 L value.Color difference is shown by the Hunter D-25 a and b values. The resultsof this series of comparative runs are set forth in Table III below.

                                      Table III                                   __________________________________________________________________________    Variation in Stock Being Treated                                                          Volume % of                                                       Type of     cyclohexyl                                                                           Evaluation of Paper Following Treatment                    Waste       pyrrolidone                                                                          Hunter D-40                                                                           Hunter D-25                                        Formula                                                                            Stock  in Cooking                     Visual Rating for                  No.  Treated                                                                              Liquor Blue                                                                              Green                                                                             L   a     b     Color and Specks                   __________________________________________________________________________    1    mixed colors                                                                         0      24.1                                                                              28.6                                                                              54.2                                                                              +24.0 + 7.39                                                                              Deep red, no specks                2      "    10     59.5                                                                              56.5                                                                              78.6                                                                              +15.5 + 3.20                                                                              Light pink, no specks              3    photomount                                                                           0      30.6                                                                              43.5                                                                              67.6                                                                              + 1.80                                                                              +14.2 Medium tan, no specks              4      "    10     57.2                                                                              70.8                                                                              84.7                                                                              + 0.60                                                                              +11.8 Cream color, no specks             5    phenolic                                                                             0      21.5                                                                              27.2                                                                              53.7                                                                              +36.6 +10.3 Deep red, no specks                6      "    10     38.7                                                                              45.1                                                                              68.6                                                                              +21.3 + 8.0 Light pink, no                     __________________________________________________________________________                                               specks                         

As seen by the results set forth in said Table III, the process andcompositions of the present invention can be used with a high degree ofeffectiveness in the deinking of various grades of difficult-to-deinkgrade material, the specific results showing the high efficiency of dyecolor, heat seal adhesive and phenolic resin removal.

EXAMPLE 2

A deinking composition consisting of 30 ml. of 3% NaOH, 28 ml. ofcyclohexyl pyrrolidone and 222 ml. of water was used to successivelycook new 3.0 grams batches of the Fort Howard Deinking Stock referred toabove for 1 hour at 170°F. After each cooking or deinking operation, theresultant pulp was defibered 2 minutes and formed into a sheet withoutfurther dilution. The cooking liquor extract from each sheet formationwas reused in the cooking of a new 3.0 gram batch. The results are asset forth in Table IV below:

                                      Table IV                                    __________________________________________________________________________    Use of Recycle CHP                                                                   Hunter D-40                                                                           Hunter D-25                                                    Cooking                    Visual Rating for Specks                           Cyclo No.                                                                            Blue                                                                              Green                                                                             L   (-)a                                                                              (+)b                                                                              and Base Sheet Color                               __________________________________________________________________________    1      69.5                                                                              75.5                                                                              88.9                                                                              2.70                                                                              5.37                                                                              No color specks; pract. white                      2      70.4                                                                              77.5                                                                              89.3                                                                              3.30                                                                              5.39                                                                                   "                                             3      69.2                                                                              77.0                                                                              89.3                                                                              4.12                                                                              5.51                                                                              No color specks; green tint (trace)                4      68.5                                                                              74.8                                                                              88.7                                                                              4.89                                                                              5.38                                                                              No color specks; slightly green                    5      68.1                                                                              75.5                                                                              88.7                                                                              5.25                                                                              5.42                                                                              Trace color specks; slightly green                 6      67.7                                                                              74.8                                                                              88.3                                                                              5.31                                                                              5.48                                                                              Trace color specks; slightly green                 Control                                                                              61.5                                                                              68.2                                                                              84.1                                                                              3.49                                                                              5.02                                                                              Very many color specks                             __________________________________________________________________________

The results shown in Table IV show that the aqueous deinking compositionfalling within the scope of the present invention can be recycled beforeeffective deinking action in at least 6 separate deinking operationsunder the conditions specified. Subsequent investigation has shown thatthe cyclohexyl pyrrolidone is not consumed, as by selective adsorption,by the pulp being treated. The alkali component of the deinkingcomposition is consumed, however, and must be replenished to maintainconstant the proportions of ingredients employed in the subject deinkingcomposition.

EXAMPLE 3

In another series of runs, the deinking process of the present inventionwas employed in the treatment of 3-part form material having 3 sheets ofNo. 4 Bond interleaved with carbon tissues, having 75% by weight of saidbond and 25% by weight of said tissue. The deinking was carried out on alaboratory scale as set forth in Example 1 and, using the same generalprocedures, in a small, 5 lb. semi-commercial beater in which the paperbeing deinked was cooked at 170°F for a period of 10-15 minutes todefiber the waste paper. In the laboratory scale runs, the cooking cyclewas 1 hour at 170°F. The results are as set forth in Tables V and VIbelow:

                                      Table V                                     __________________________________________________________________________    Deinking of 3-Part Form                                                       (170°F cook at 10-15 min. in 5 lb beater)                              % NaOH     Vol. % CHP in                                                                          Hunter D-25                                               Trial No.                                                                           (owf)                                                                              Cooking Liquor                                                                         L   a   b    Appearance                                   __________________________________________________________________________    1     10   0        35.1                                                                              2.88                                                                              -3.46                                                                              blue, speckled                               2     10   5        73.9                                                                              0.28                                                                              4.90 near white                                   3     10   3        76.0                                                                              0.74                                                                              4.97 near white                                   4     10   1        73.3                                                                              0.78                                                                              2.42 sl. blue tint                                5     10   0.75     69.7                                                                              0.67                                                                              -0.40                                                                              sl.→mod. blue tint                    __________________________________________________________________________

                  Table VI                                                        ______________________________________                                        Deinking of 3-Part Form                                                       (170°F cook for 1 hr. in blender)                                      Vol. %                                                                        CHP in                                                                        Cooking                                                                       Liquor L       a       b      Appearance                                      ______________________________________                                        0      60.62   2.78    -5.22  grey, some black specks                         5      66.16   1.18    -0.82  large blue spots                                ______________________________________                                    

As can be seen from the results of said Tables V and VI above,relatively small amounts of the subject N-alkyllactam solvent arerequired in the aqueous deinking composition of the invention foreffective deinking of the waste paper being treated. The results alsoindicate that the desired deinking effect is enhanced in the large scaledeinking equipment, it being generally understood that the effectivenessof the aqueous deinking composition of the invention is enhanced in thecarrying out of the invention is commercially available deinkingequipment.

EXAMPLE 4

A further series of deinking runs was carried out using theabove-mentioned 3-Part form waste material cooked at 170°F for 1 hourusing a variety of inorganic salts in the aqueous deinking composition.The salts were added to the composition as 3% by weight solutions inwater, with 30 ml. of the solution employed. 3 Grams of the substratematerial being deinked were employed per 280 grams of the overallaqueous deinking composition of the invention. The results are as setforth in Table VII below:

                                      Table VII                                   __________________________________________________________________________    Variation in Inorganic Salts Employed in the Aqueous Deinking                 Composition                                                                          CHP Vol.      Hunter D-25                                              Salt Used                                                                            (% of Deinking Solution)                                                                    L    a    b     Appearance                               __________________________________________________________________________    NaOH   0             60.62                                                                              +2.78                                                                              - 5.22                                                                              many large blue spots                    NaOH   5             66.16                                                                              +1.18                                                                              - 0.82                                                                              mod. spots-grey white                    KOH    0             64.54                                                                              +2.15                                                                              - 3.82                                                                              many large blue spots                    KOH    5             65.66                                                                              +1.38                                                                              - 1.28                                                                              mod. spots grey white                    Ca(OH).sub.2                                                                         0             57.47                                                                              +1.91                                                                              - 7.90                                                                              very many spots-blue                     Ca(OH).sub.2                                                                         5             66.20                                                                              +1.85                                                                              + 0.82                                                                              mod. spots-grey white                    FeCl.sub.3                                                                           0             54.91                                                                              -0.44                                                                              + 9.84                                                                              very many spots-yellow color             FeCl.sub.3                                                                           5             59.32                                                                              -0.74                                                                              +12.99                                                                              mod. spots-yellow                        Al.sub.2 (SO.sub.4).sub.3                                                            0             57.47                                                                              +1.17                                                                              -11.14                                                                              very many spots                          Al.sub.2 (SO.sub.4).sub.3                                                            5             59.50                                                                              +2.01                                                                              -11.12                                                                              mod. spots                               __________________________________________________________________________

From the results set forth in Table VII, it can be seen that althoughNaOH is commonly employed in conventional deinking operations and isadvantageous from an economic and technical viewpoint, other commonlyavailable inorganic salts may effectively be employed in the practice ofthe present invention. The presence of such soluble inorganic salts,having cations such as sodium, calcium, iron, aluminum, magnesium andthe like, serve to reduce the solubility in water of the N-alkyllactamsolvent employed at the cooking temperature employed. While the waterthus serves as an appropriate carrier to assure adequate contacting ofthe paper being treated with the lactam solvent employed, the relativelylow water solubility of the lactam solvent at the indicated deinkingtemperatures in the presence of soluble inorganic salts of the type setforth above enhances the effectiveness of the deinking operation. Thus,insoluble N-alkyllactam solvent is available for effective deinking ofthe moist paper with which it is brought into contact. In similar runscarried out as set forth in said Example 4, the addition of thecyclohexyl pyrrolidone to the deinking composition resulted in somevisual improvement in the appearance of the treated pulp, reducingsomewhat the number of small spots thereon, but did not favorablyimprove the brightness as indicated by the Hunter D-25 measurements.From these results, it can be inferred that preferred embodiments of theaqueous treating composition of the present invention will contain oneor more of the water soluble, inorganic ionic salts disclosed andclaimed herein having the indicated cations thereby present in theaqueous treating composition.

EXAMPLE 5

The above-mentioned procedure of Example 1 was employed in a series oftest runs using 3.0 grams of the above-mentioned Fort Howard DeinkingStock in each run for treatment with aqueous deinking compositionscontaining t-Octyl-2-pyrrolidone, N-t-butylpyrrolidone andN-methylpyrrolidone as the N-alkyllactam solvent. The results of thisseries of runs are shown below in Table VIII:

                                      Table VIII                                  __________________________________________________________________________    Variation in N-Alkyllactam Solvent                                                           Vol. %  Evaluation of Paper Following Deinking                         ml. Pyrr.                                                                            Pyrr.   Hunter D-40                                                                           Hunter D-25                                    Run ml. 3%                                                                            in     in  ml.                                                        No. NaOH                                                                              Liquor Liquor                                                                            H.sub.2 O                                                                         Blue                                                                              Green                                                                             L  (-)a                                                                              (+)b                                                                              Visual Rating for Base Color                                                  and Specks                          __________________________________________________________________________    1   30  0  --   0  250 63.1                                                                              68.5                                                                              84.9                                                                             2.92                                                                              4.59                                                                              Very many specks                    2   30  28 Cyclo                                                                             10  222 69.4                                                                              75.4                                                                              89.7                                                                             3.69                                                                              4.49                                                                              Pract. white - no specks                       Pyrr.                                                              3   30  14 Oct  5  236 65.3                                                                              72.7                                                                              86.2                                                                             6.69                                                                              4.95                                                                              Green tin - moderate green                                                    flakes                                         Pyrr.                                                              4   30  28 Oct 10  222 66.6                                                                              71.5                                                                              86.5                                                                             6.69                                                                              3.85                                                                              Green tint - moderate (+) green                                               flakes                                         Pyrr.                                                              5   30  56 Oct 20  194 69.7                                                                              74.9                                                                              87.1                                                                             5.17                                                                              3.81                                                                              Greent tint - slight green                                                    flakes                                         Pyrr.                                                              6   30  14 Butyl                                                                              5  236 63.9                                                                              70.6                                                                              87.4                                                                             3.40                                                                              5.93                                                                              Pract. white - moderate specks                 Pyrr.                                                              7   30  28 Butyl                                                                             10  222 70.9                                                                              77.5                                                                              90.3                                                                             2.78                                                                              5.80                                                                              Pract. white - sli. - moderate                                                specks                                         Pyrr.                                                              8   30  56 Butyl                                                                             20  194 67.6                                                                              71.8                                                                              87.0                                                                             3.68                                                                              4.04                                                                              Pract. white - apprec. specks                  Pyrr.                                                              9    0  28 Oct 10  252 65.5                                                                              69.2                                                                              84.9                                                                             2.68                                                                              3.42                                                                              Very many specks                               Pyrr.                                                              10   0  28 Butyl                                                                             10  252 60.5                                                                              62.3                                                                              81.0                                                                             3.31                                                                              1.79                                                                              Very many specks                               Pyrr.                                                              __________________________________________________________________________

From the results set forth in Table VIII, it can be seen that effectivedeinking is accomplished with either N-cyclohexyl pyrrolidone,N-t-butyl-pyrrolidone or t-octyl-2-pyrrolidone as the N-alkyllactamsolvent employed in the aqueous deinking composition of the invention.N-t-butyl-pyrrolidone is found to be additionally advantageous in thatits use in the deinking operation results in very high foam developmentof significance with respect to flotation-type deinking operations.N-octylpyrrolidone, although of lesser foam producing capability,nevertheless forms a very stable surface foam during the deinking, orcooking, operation. The foam serves to hold fiber fines, pigment andother suspended matter at the surface, facilitating removal by raking orsuch mechanics commonly employed in flotation deinking operations.

EXAMPLE 6

N-methylpyrrolidone was also employed in the deinking of a 3.0 grambatch of the Fort Howard Deinking Stock using the general procedures ofExample 1. The results were as set forth in Table IX below:

                                      Table IX                                    __________________________________________________________________________    N-Methylpyrrolidone as N-Alkyllactam Deinking Solvent                         Formula Composition                                                                                Evaluation of Paper Following Deinking                      ml. ml.                                                                    Run                                                                              3%  20% ml.   ml. Hunter D-40                                                                           Hunter D-25    Visual Rating for Base            No.                                                                              NaOH                                                                              NaOH                                                                              M-Pyrol                                                                             H.sub.2 O                                                                         Blue                                                                              Green                                                                             L   a    b     Sheet Color and                   __________________________________________________________________________                                                Specks                            1  30  0   0     250 60.7                                                                              65.4                                                                              82.9                                                                              -3.60                                                                              + 4.20                                                                              Very many specks                  5   0  4.5 250   0   45.4                                                                              59.3                                                                              78.6                                                                              +0.78                                                                              +12.78                                                                              Medium tan - no                   __________________________________________________________________________                                                specks                        

The results set forth in Table IX show that the deinking of the wastepaper stock employing about 97% by weight N-methyl pyrrolidone waseffective in removing all specks from the treated paper, whereas aconventional cooking liquor having an equivalent alkali content, whileadvantageous in some brightness measurements, did not remove all specks,but left many specks as were readily apparent on visual analysis.

The effectiveness of N-alkyllactam solvents, when employed in aqueousdeinking compositions in accordance with the teachings of the invention,represents a major advance in reclaiming plastic-treated papers. Evenwhen such difficult-to-deink grade material is present in very smallquantities, it can spoil otherwise acceptable waste paper if noteffectively deinked. In continuous deinking operations, as in theembodiments illustrated in the drawing, it is highly important from anoverall economic viewpoint to regenerate and reuse the N-alkyllactamsolvent to the fullest possible extent. In this regard, it issignificant to note that the N-alkyllactam solvent is not consumed ordestroyed in the deinking operation. The aqueous deinking solutionpressed from the treated pulp can generally be recycled to the pulper atleast eight times without regeneration, alkali, or other additionalinorganic components referred to above, is consumed and will besupplemented with make-up material to maintain a desired concentrationthereof. In commercial applications of the invention, the amount ofaqueous deinking composition recycled from the press to the pulper mayvary depending upon a number of factors such as the consistency utilizedin the pulper, the pulp shrinkage, the desired consistency leaving thepress, the particular grade of paper being treated, the particularaqueous deinking composition employed, the operating conditions and thelike. In general, however, the amount of said deinking compositionrecycled from the press to the pulper will constitute a major portion ofthe deinking composition content of the pulp fed to the press. The saidrecycle aqueous deinking composition will thus generally be at least 50%by weight, typically from about 50% to about 75% by weight, of thedeinking composition withdrawn from the pulper. The remaining deinkingcomposition passes to the washing zone with the treated pulp and isthereafter recovered, regenerated and recycled to the pulper as hereinprovided.

N-alkyllactam solvent present in the wash water solution can berecovered as by concentration of said solution and distillation thereofto produce a purified lactam solvent stream for recycle and reuse in thecontacting of additional quantities of the waste paper being treated. Inparticularly advantageous embodiments of the invention, the simplifiedregeneration techniques disclosed above and illustrated in the drawingcan be employed because of the phase separation, or cloud pointcharacteristics, of particular N-alkyllactam solvents. As previouslyindicated, aqueous solutions of N-cyclohexyl pyrrolidone, N-t-butylpyrrolidone and t-octyl-2-pyrrolidone containing dissolved wastematerials will undergo such advantageous phase separation at particularcloud point temperatures dependent on the concentration thereof in theaqueous wash solution, the amount and nature of the wastes associatedtherewith, etc. For as complete solvent recovery and reuse as possible,the water-rich layer formed by such desirable phase separation will berecycled for further use in the pulping zone. It will be appreciatedthat the solvent content of the water layer, which will generally besmall but of importance from an overall economic viewpoint, will varydepending upon the materials employed and the operationg conditionspertaining to a given deinking-solvent regeneration operation. In atypical illustrative example, presented simply to indicate arepresentative breakdown of solvent distribution in the two separate anddistinct layers, a cyclohexyl pyrrolidone and water wash solution,having particular wastes therein and maintained at about 200°F, mayseparate into a water-rich layer comprising about 3/4 of the totalvolume of said wash solution and containing about 7.5% solvent based onthe total volume of said water-rich layer, and a solvent-rich layercomprising about 1/4 of the total volume of said wash solution andcontaining about 50% solvent based on the total volume of saidsolvent-rich layer. As herein provided, essentially all of the solventis recycled to the pulping zone in preferred embodiments of theinvention. It should be noted that, with respect to various exampleshereinabove set forth using N-cyclohexyl pyrrolidone, the specificgravity of the solvent is approximately the same as that of water, theproportions of said solvent expressed in % by volume being approximatelythe same as the proportion of said solvent expressed in % by weight.

The aqueous treating compositions herein disclosed and claimed for usein the deinking of waste paper have also been found to be of advantagein other novel applications of commercial significance. Thus, aqueoussolutions containing the subject N-alkyllactam solvents can be employedin the pulping of wood chips, the bleaching of crude pulp, the washingof brown stock to increase fine screen yield and reduce sulfate losses,the removal of natural and synthetic color bodies from pulp and papermill effluents and white water. Other potential applications of suchaqueous treating compositions are in improving the dissolving andextrusion characteristics pertaining to the conversion of cellulose toxanthate, viscose, and cellophane, in adhesives and in printing inkvehicles, plasticizers and the like in the general field of pulp andpaper treatment and conversion. In the pulping of wood chips, theaqueous treating composition of the invention containing the subjectN-alkyllactam solvent can be employed in conventional paper millequipment, in which evoking times on the order of about 6 hours at about330°F and about 100 psig are employed in typical operations, inachieving lower cooking cycles, improved pulp yield and/or quality, morefavorable operating conditions or some combination of such desirablefeatures in the treatment of various grades of wood chips.

The reclamation of waste materials is of ever increasing significanceand importance in all aspects of industrial and economic activities. Thereclamation of waste paper is of particular concern and importance inlight of the tremendous modern usage of paper and paper products. Fullutilization of waste paper through reclamation procedures is impaired,however, by the increasing use of difficult-to-deink grade material, asin thermoplastic or elastomeric treated paper. As indicated above, evena relatively small quantity of such difficult-to-deink grade materialcan spoil an otherwise acceptable batch of waste paper. For generalacceptance in commercial deinking operations, a deinking compositionand/or technique should desirably be effective in use with respect to awidely diverse range of waste papers containing specialized plastic orwax coatings, adhesives, waxes, inks and the like. Such techniques mustalso, of course, be economically feasible and, as such, generallynecessitate effective regeneration and reuse of solvents or other suchcomponents employed in place of or in addition to conventional deinkingingredients. The process and compositions of the present invention arehighly effective, useful with respect to a wide range of waste papermaterials, particularly of advantage in the deinking ofdifficult-to-deink grade materials, and capable of essentially completesolvent recovery, regeneration and reuse in continuous deinkingoperations. This highly desirable combination of effective deinking inapplications for which conventional techniques are generally not suited,together with economical regeneration and compatibility with commonlyavailable capital equipment, renders the present invention of greatsignificance in the field of waste paper reclamation. The environmentalimportance of the invention in the reclamation of the increasingquantities of wastes comprising difficult-to-deink grade material isenhanced by the essentially complete recovery of the N-alkyllactamsolvents. Thus, the practice of the invention not only tends to minimizeany inadvertent waste material discharge, as in wash water effluent, butlikewise obviates any undesired contamination of said effluent by thetreating solvent itself. The invention thus represents a majorindustrial and environmental advance in the reclamation of paper wastematerials.

Therefore, we claim:
 1. A waste paper pulp deinking compositioncontaining between about 1 and about 20 weight percent waste paper basedon the weight of the waste paper deinking composition employed and awaste paper deinking composition comprising from about 0.5 to about 200parts by weight of water, from about 0.05 to about 1 part by weight of awater-soluble non-volatile, inorganic ionic compound containing a cationtaken from the group consisting of sodium, potassium, calcium, iron,aluminum and magnesium, and from about 0.75 to about 25 weight percentof an N-alkyllactam solvent.
 2. The composition of claim 1 in which saidN-alkyllactam comprises an N-lower alkyl pyrrolidone.
 3. The compositionof claim 2 in which said N-lower alkyl pyrrolidone comprisesN-cyclohexyl pyrrolidone.
 4. The composition of claim 2 in which saidN-lower alkyl pyrrolidone comprises N-t-octyl pyrrolidone.
 5. Thecomposition of claim 2 in which said N-lower alkyl pyrrolidone comprisesN-t-butyl pyrrolidone.
 6. The composition of claim 2 in which saidN-lower alkyl pyrrolidone comprises N-methyl pyrrolidone.
 7. Thecomposition of claim 1 in which said cation comprises sodium.
 8. Thecomposition of claim 7 in which said inorganic compound comprises sodiumhydroxide.
 9. The composition of claim 8 in which said N-alkyllactamcomprises N-cyclohexyl pyrrolidone.